On Birthday

What is the sense, or meaning of a birthday for an adult? I guess its importance relates not to receiving presents or organizing parties and having some fun, although some people may very much enjoy these things. I think BD can give a mature person a sense of thankfulness for the life, opportunity for remembering and acknowledging his or her parents, accepting respect and love of the closest people, and appreciation of himself or herself and the loved ones. It is a positive reflection and feeling day.